(a) Field of the Invention
The present invention relates to a chip light emitting diode and a fabrication method thereof.
(b) Description of the Related Art
Chip light emitting diodes (LEDs) are generally employed as display devices and for backlighting. Recently, their use range has been increased to include various applications such as light sources for mobile phones and personal digital assistants (PDAs).
Referring to FIG. 1, a conventional chip LED 50 is provided with a metal pad 52 and a lead 55 on a printed circuit board (PCB) 51. A light emitting chip 53 mounted on the metal pad 52 is connected to the lead 55 via a wire 54. A resin package 56 is formed of an epoxy mold compound (EMC), and seals the chip 53.
The conventional chip LED 50 has drawbacks in that optical paths of emitted light rays are limited because the resin package 56 has a rectangular cross section, causing a narrow viewing angle of the chip LED. Further, the intensity distribution of the emitted light is concentrated at the position of the chip. Therefore, many chip LEDs are required to light a certain area, resulting in high manufacturing cost in some applications such as for backlighting.
Further, heat generated from the conventional chip LED 50 during operation is concentrated in the edges, resulting in thermal or mechanical deformation of the diode.
When the thickness of the resin package is reduced for overall compactness of the conventional chip LED, a metal mold of the resin package should be more precisely formed for the edges, which may result in high manufacturing costs. Further, when the thickness of the resin package happens to be not uniform, stress may be concentrated at a thin part, so the adhesive strength is deteriorated causing poor reliability of the chip LED.